One of causes of data errors in IC (integrated circuit) includes an influence of high frequency noise. Known is a method for inhibiting the above matter in which a capacitor having a large capacity is provided on a wiring board to remove high frequency noise. A capacitor having such a large capacity is produced by forming a high dielectric constant layer on a wiring board. Further, a size of a built-in antenna and a thickness of a wave absorber are almost inversely proportional to a square root of a dielectric constant, and therefore a high dielectric constant material is useful for a reduction in a size and a reduction in a thickness of the above members. In particular, resin materials which are excellent in a processability and a moldability are required to be endowed with the above characteristic.
A resin composite material in which 65 vol % or more, that is, 80 wt % or more of a strong dielectric substance represented by barium titanate is filled as a high dielectric constant filler is proposed as a conventional technique of a high dielectric constant resin composite material (refer to, for example, a patent document 1). On the other hand, a high dielectric constant composition for coating a conductive powder with an insulated film by a thermosetting resin is proposed (refer to, for example, a patent document 2). However, the stable performance is not obtained, and therefore it is not commercially produced. Further, a method for coating a metal powder with metal oxide (refer to, for example, a patent document 3) is proposed in recent years. However, it has to be filled at a high level as is the case with conventional high dielectric constant fillers, and in addition thereto, a metal powder has usually a higher specific gravity than that of metal oxide, so that a specific gravity of a high dielectric constant resin composite material is as further large as 3 or more.
Further, proposed as well is a method in which a material prepared by winding a high polymer around a single layer carbon nanotube to insulate it is used for a rise in a dielectric constant of a resin material (refer to, for example, a patent document 4). In the above method, however, the wound high polymer which corresponds to an insulated coating film can reversibly be peeled off, and therefore the problem that the stable performance is not obtained has been involved therein.
Consequently, the existing situation is that in fact, a method in which a large amount of the filler described above is added is used. Accordingly, a processability, a moldability and a light weight which are the intrinsic characteristics of a resin material are damaged in exchange for a rise in a dielectric constant thereof.
In order to solve the above problems, the present inventors have disclosed previously an insulated ultrafine powder prepared by coating a specific conductive ultrafine powder with specific metal oxide and a high dielectric constant resin composite material prepared by using the above insulated ultrafine powder (refer to, for example, patent documents 5 and 6).